1. Field of the Invention
The present invention relates to a method of forming a groove with desired cross sections by irradiating a laser beam to a work, and more particularly to a method of easily forming the groove which has a constant depth in a scanning direction and an arbitrary depth distribution in the direction vertical to the scanning direction by relatively moving the irradiated area on the work.
2. Description of the Related Art
As a method of forming a groove having various figures of cross sections by a laser beam aberration, a method of irradiating a slit-shaped laser beam converted through a projection mask to the surface of a work, which is moved in the width direction synchronizing to the laser beam pulse oscillation (Japanese Patent Laid-open No. 8-19878) is known.
However, the prior method described above have several problems. In accordance with the method, a complicated and precise control of a scanning velocity is needed to form a desired cross section because a depth of the groove depends on the scanning velocity of the slit-shaped laser beam in the width direction. Furthermore, a period of controlling the scanning velocity, which is modulated in accordance with a desired cross sectional figure, is necessary to be repeated at each time when the laser beam on the work is moved little by little in the longitudinal direction of the groove. Accordingly, in conventional methods, a complicated control for displacement and velocity of the work is required and a large amount of manufacturing time is required because of scanning in two directions of the x-axis and the y-axis.